<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    /* .wrap{
      width: 800px;
      height: 500px;
      background: #ccc;
    } */
    .left{
      width: 200px;
      height: 400px; 
      background: red;
      float: left;
    }
    .center {
    width: calc(100% - 350px);
    height: 450px;
    background: seagreen;
    float: left;
  /* overflow: hidden; */
}
    .right{
      width: 150px;
      height: 350px;
      background: blue;
      /* overflow: hidden; */
      float: left;
    }
  </style>
</head>
<body>
  <!-- <div class="wrap"> -->
    <div class="left"></div>
    <div class="center"></div>
    <div class="right"></div>
  <!-- </div> -->
</body>
</html>
<!-- 
  calc:
  用于处理简单四则混合运算的功能函数
  注意：运算符的前后必须有空格
 -->